The present invention relates to machine tools in general, and more particularly to improvements in tool supports for use in turning machines, especially in turning machines of the type wherein the tool support is mounted on a slide and the workpiece is held in a rotary work spindle.
Many types of machine tools are provided with automatic tool changers which exchange tools without any supervision or manipulation by the persons in charge. As a rule, such machines are equipped with a tool magazine and the automatic tool changer or tool changers are designed to transport discrete tools between the magazines and the tool holder of the machine. Each tool changer normally operates in such a way that it transports a fresh tool during movement away from the magazine and returns a previously used tool during travel toward the magazine. Tool magazines and automatic tool changers are desirable and practical in large machine tools and in huge production lines but they are less practical or cannot be used at all in relatively small machine tools, for example, in connection with many types of automatic turning machines. The space requirements of a magazine and tool changer are normally such that these parts cannot be readily installed in, on or adjacent to a relatively small turning machine or an analogous machine tool. Moreover, tool magazines and automatic tool changers are not practical for use in machine tools wherein the tools must be exchanged at frequent intervals because the total time which is taken up for exchange of tools constitutes a substantial percentage of the time during which the machine tool is in actual use. This holds especially true when the tool magazine must be installed at a relatively large distance from the working station so that the tool changer must transport the tools along an elongated path. Still further, when the tools must be exchanged at frequent intervals, the likelihood of penetration of foreign matter into the sockets for tools or tool holders is quite pronounced. If a chip, shaving or another foreign particle happens to enter a socket, the tool holder or the tool which is thereupon inserted into the same socket is not held in an optimum position so that the configuration and/or finish of the workpiece is unsatisfactory. It is well known that drills, turning tools and other types of tools which are used in relatively small automatic turning machines must be interchanged at frequent intervals; consequently, inaccurate finish of workpieces due to penetration of foreign matter into the sockets for such tools of their holders is to be be expected if the sockets remain empty for prolonged periods of time or at frequent intervals. Therefore, all presently utilized automatic turning machines employ reciprocal tool carriages or indexible tool turrets which support holders for several material removing tools. It was also proposed to provide the turret or carriage of a machine tool with two or more rows of sockets for tool holders to thereby increase the overall number of tools which can be held in readiness close to the working station. Such mounting of tool holders in several rows renders it possible to treat a workpiece with two tools in a simultaneous operation, for example, to remove material by means of a turning tool and a borer.
A drawback of the just described machine tools is that the treatment of each type of workpieces necessitates a different setup of tools in the tool support, regardless of whether the tool support constitutes a turret or a carriage. Thus, whenever the machine has completed the treatment of a batch of workpieces and is to treat a batch of different workpieces, the tools in the tool support must be rearranged and/or replaced with different tools. This is due to the fact that, when the tools are mounted in a turret, the latter is merely movable in the axial direction of the work spindle. A tool carriage in presently known machine tools is movable in a direction at right angles to the axis of the work spindle. For example, when the tools are mounted in an indexible turret which is movable only axially of the work spindle, a turning tool which is to remove material from the front end face of a workpiece in the chuck of the work spindle cannot be used in such a machine tool because the turret would be unable to move the turning tool radially of the work spindle.